Published online: 12 Aug 2014.

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1 This article was downloaded by: [E. Arthur Shores] On: 16 August 2014, At: 02:05 Publisher: Routledge Informa Ltd Registered in England and Wales Registered Number: Registered office: Mortimer House, Mortimer Street, London W1T 3JH, UK Applied Neuropsychology: Adult Publication details, including instructions for authors and subscription information: A Comparison of the Degree of Effort Involved in the TOMM and the ACS Word Choice Test Using a Dual-Task Paradigm Lucienne Isabel Barhon a, Jennifer Batchelor a, Susanne Meares a, Eugene Chekaluk a & E. Arthur Shores a a Psychology, Macquarie University, Sydney, Australia Published online: 12 Aug To cite this article: Lucienne Isabel Barhon, Jennifer Batchelor, Susanne Meares, Eugene Chekaluk & E. Arthur Shores (2014): A Comparison of the Degree of Effort Involved in the TOMM and the ACS Word Choice Test Using a Dual-Task Paradigm, Applied Neuropsychology: Adult, DOI: / To link to this article: PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the Content ) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at

2 APPLIED NEUROPSYCHOLOGY: ADULT, 0: 1 10, 2014 Copyright # Taylor & Francis Group, LLC ISSN: print= online DOI: / A Comparison of the Degree of Effort Involved in the TOMM and the ACS Word Choice Test Using a Dual-Task Paradigm Lucienne Isabel Barhon, Jennifer Batchelor, Susanne Meares, Eugene Chekaluk, and E. Arthur Shores Psychology, Macquarie University, Sydney, Australia Downloaded by [E. Arthur Shores] at 02:05 16 August 2014 Key words: The aims of the current study were to: (a) examine the predictive validity and efficacy of the Advanced Clinical Solutions Word Choice Test (WCT) as a measure of effort relative to the Test of Memory Malingering (TOMM); (b) investigate whether performing a dual (distraction) task would undermine performance on either test; (c) assess the effect of coaching on the diagnostic accuracy of both the WCT and the TOMM; and (d) establish an optimal cut score for the WCT. The current study used a simulation design based on an analogue design in which normal participants were instructed to either apply full effort or simulate a brain injury on the tasks without being detected. Participants included 93 undergraduate university students who were randomly assigned to 1 of 4 conditions: (a) distraction, (b) uncoached traumatic brain injury (TBI) simulators, (c) coached TBI simulators, or (d) full effort. The results demonstrated that the WCT and the TOMM were effective in detecting simulated cognitive impairment. Both tests were resistant to the effects of distraction and were equally effective in detecting coached and uncoached simulators. A cut score of 42 on the WCT was found to provide optimal specificity and sensitivity on the test. neuropsychology, symptom validity testing, tests Although the Test of Memory Malingering (TOMM; Tombaugh, 1996) is a well-validated and widely used measure of effort (Axelrod & Schutte, 2011; Merten, Boosink, & Schmand, 2007; O Bryant & Lucas, 2006; Powell, Gfeller, Hendricks, & Sharland, 2004; Rees, Tombaugh, Gansler, & Moczynski, 1998; Tombaugh, 1997), the fact that information regarding the content, procedure, and cut scores of the test is readily available on multiple Web sites (Bauer & McCaffrey, 2006) poses serious threats to the test s validity. Although there are a number of existing measures of effort, it has been argued that there is a need to develop new alternative measures for which the availability of information is regulated (Bauer & McCaffrey, 2006; Suhr & Gunstad, 2007). Address correspondence to Lucienne Isabel Barhon, Psychology, Macquarie University, Balaclava Rd., North Ryde, Sydney, 2109 Australia. lucienne.barhon@students.mq.edu.au The Word Choice Test (WCT; Pearson, 2009) forms part of the Advanced Clinical Solutions (ACS) package and represents another free-standing symptom validity test (SVT). To date, there has been only one study published on the WCT, in which it was reported that in a traumatic brain injury (TBI) sample, the WCT had a sensitivity of 72% and specificity of 89% (Miller et al., 2011). In this study, the good effort group included those patients with moderate-to-severe TBI who failed no more than one of the five administered SVTs, and the suspect effort group included those who failed two or more SVTs. This study demonstrated that the WCT added to the diagnostic accuracy of the ACS. Miller et al. (2011) offered an equation which reveals that a score of 41 or less is suggestive of poor effort on the WCT ([WCT 0.216] 9.022). The WCT needs to be independently validated in severely impaired individuals. In contrast, there has been a large amount of literature validating the TOMM as a measure of effort. Although

3 2 BARHON ET AL. the TOMM has been found to have a high level of specificity, there has been variability in the literature regarding the sensitivity of this measure (Gervais, Rohling, Green, & Ford, 2004; Iverson, Lange, Brooks, & Rennison, 2010; Rees et al., 1998). Specifically, in very impaired populations such as patients with severe dementia, the TOMM has been found to have a high false-positive rate, whereas in TBI samples, the falsepositive rate is low (Iverson et al., 2010; Merten et al., 2007; Pivovarova, Rosenfeld, Dole, Green, & Zapf, 2009; Rees et al., 1998; Teicher & Wagner, 2004; Tombaugh, 1996, 1997). That the TOMM may have low sensitivity has been demonstrated in both clinical and undergraduate samples (An, Zakzanis, & Joordens, 2012; Armistead-Jehle & Gervais, 2011). The TOMM has been demonstrated to be insensitive to age, education, mood disturbance, and all but the most severe dementias (Merten et al., 2007; Pivovarova et al., 2009; Tombaugh, 1996). Rees et al. (1998) reported the measure to have 100% specificity and 84% to 100% sensitivity across a series of five validation experiments. Using a base rate of 30%, O Bryant and Lucas (2006) reported the TOMM to have a positive predictive value (PPV) of 98% and a negative predictive value (NPV) of 78%. Demonstrating that a measure of effort is specific to poor effort or malingering and therefore insensitive to true cognitive impairment is an important aspect of test validity. That is, the test should primarily measure effort alone and not require any significant cognitive ability (Batt, Shores, & Chekaluk, 2008; Heilbronner et al., 2009). Dual-task paradigms provide one means of demonstrating that a test does not require cognitive ability as dual tasking reduces the individual s capacity to perform at their best without affecting effort. The distraction caused by dual tasking precludes encoding and accordingly reduces the ability to learn information. Dual tasking therefore reduces the ability to perform at one s best, without reducing effort or motivation. In keeping with that contention, Batt et al. (2008) demonstrated that on the TOMM, there was no difference between the performance of those participants fully attending to the task and those who were simultaneously completing a distraction task, suggesting that performance on the TOMM is largely independent of cognitive ability. To date, the effects of distraction on the WCT have not been investigated. One factor that has been recognized to potentially undermine psychological test validity is coaching (Brennan et al., 2009). It has been reported that a large number of attorneys routinely coach their clients on how to approach neuropsychological tests (Brennan et al., 2009; Jelicic, Ceunen, Peters, & Merckelbach, 2011; Powell et al., 2004; Russler, Brett, Klaue, Sailer, & Munte, 2008; Suhr & Gunstad, 2007). Studies investigating the effects of coaching on the TOMM found that although coaching reduced the incidence of detection, the TOMM still detected 80% to 87% (Jelicic et al., 2011) and 93% to 96% (Powell et al., 2004) of coached TBI simulators. Therefore, it is possible that although coaching may cause more sophisticated simulating, it does not necessarily result in a failure of detection on tests of effort. The effects of coaching on the WCT have yet to be examined. One commonly used study design to investigate malingering is a simulation design, where participants are instructed to simulate a condition (such as to malinger the cognitive symptoms of a TBI) while completing tests designed to detect exaggeration in order to assess test efficacy (Erdal, 2004; Heilbronner et al., 2009). Although simulation designs have a number of potential limitations, such as low external validity, inflation of observed specificity, and the potential for a lack of adequate motivation in participants to truly replicate the behavior of a malingerer, there are also a number of benefits (Erdal, 2004; Larrabee, 2007; Powell et al., 2004) for example, confidence of group membership of participants, high internal validity, and confidence that the changes observed in the dependent variables are a result of the experimental manipulations (Larrabee, 2007; Vickery et al., 2004). The aims of the current study were to: (a) examine the predictive validity and efficacy of the WCT as a measure of effort relative to the TOMM; (b) investigate whether performing a dual (distraction) task would undermine performance on either test; (c) assess the effect of coaching on the diagnostic accuracy of both the WCT and the TOMM; and (d) establish an optimal cut score for the WCT. It was hypothesized that there would be no significant difference in the number of simulators detected by the WCT and the TOMM. Further, it was anticipated that performance of the groups applying full effort (full-effort and distraction groups) on both the WCT and the TOMM would be significantly better than that of the two groups instructed to simulate a TBI (coached and uncoached). Therefore, within an undergraduate population, it was expected that the TOMM and the WCT would be of comparable sensitivity and that a comparable degree of effort would be required to complete both measures. It was also hypothesized that performance of the distraction group on the TOMM and on the WCT would not differ from that of the full-effort group. Lastly, it was expected there would be no significant difference between the number of those in the coached and uncoached groups detected by either the WCT or the TOMM. A specific cut score was unable to be hypothesized as it could only be determined by the results returned by the current sample.

4 METHODS Participants Participants were 93 undergraduate psychology students from Macquarie University, most of whom (n ¼ 83) were completing the 1st year of their degree. Each participant completed a two-item manipulation check at the end of the testing session to ensure compliance and effort to follow the given instructions. Participants were asked to rate how much effort they applied toward following their given instructions and how easy it was to follow the instructions. The results of 1 participant were excluded from the analysis due to a reported lack of compliance with test instructions, leaving a final sample size of 92 participants included in the analysis. Those in their 1st year were recruited via an online research participant pool and received course credit for their participation. The remainder participated voluntarily by responding to posters advertising the study. The names of these participants went into a draw for the chance to receive a $50 gift voucher. Three participants reported a history of neurological illness; however, they were not excluded from the analysis, as their scores did not differ from the means obtained by their assigned groups. Procedures and Measures Participants were randomly assigned to the two groups applying full effort (full-effort and distraction groups) and to the two groups instructed to simulate a TBI (coached and uncoached). Power calculations revealed that a sample size of 20 in each group was required to obtain a power of.8 and an effect size of.8 at 95% confidence. All participants gave written consent to participate in the study. A short demographic questionnaire, which contained questions pertaining to age, sex, years of education, and any history of neurological illness, was given to each participant to complete. Word Choice Test (Pearson, 2009). The WCT is a single-trial measure of effort that is described as a test of memory for common words (Pearson, 2009). The WCT is very similar in format to the Word subtest of the Warrington Recognition Memory Test (RMT; Warrington, 1984), although different stimuli (words) are employed. The stimulus booklet for the WCT contains 50 common words, which are individually presented both visually and verbally. Participants are then required to recognize the word previously shown, in a dichotomous forced-choice response format, from pairs of words containing one target and one foil. The WCT, like the TOMM, is scored out of 50, with a score COMPARISON OF THE TOMM AND THE WCT 3 of 1 for each correct response and a score of 0 for each incorrect response. Due to the high number of false positives on the Warrington RMT in patients with severely impaired dementia, the WCT may similarly be sensitive to the cognitive deficits present in severely impaired individuals. The Test of Memory Malingering (Tombaugh, 1997). The TOMM is a three-trial (Trial 1, Trial 2, and Retention Trial) pictorial measure of effort, which was originally designed for use as a test of memory in patients with dementia but was later recognized to be insensitive to memory impairment in many other conditions (Rees et al., 1998; Tombaugh, 1996, 1997). The Retention Trial was not administered in the current research as the two learning trials have been reported to be sufficient in discriminating between simulators and those applying full effort, with minimal increase in sensitivity being gained from administering the last trial (Tombaugh, 1996). The cut score of 45 out of 50 (44 or less indicating a fail) on Trial 2 has been consistently found to correctly discriminate simulators from those applying full effort with very few genuinely cognitively impaired participants scoring below this point (Powell et al., 2004; Rees et al., 1998; Tombaugh, 1996). Therefore, only Trial 2 was used in the analyses to identify detection of those simulating a TBI. In the present study, the TOMM was used as the gold standard with which to compare results on the WCT. The TOMM is commonly employed and widely accepted as a measure of effort in current clinical practice. The TOMM has been found to have high specificity, although the sensitivity of this measure has varied across studies (Gervais et al., 2004; Green, 2011; Iverson et al., 2010; Merten et al., 2007; Pivovarova et al., 2009; Rees et al., 1998; Teicher & Wagner, 2004; Tombaugh, 1996, 1997). Sharland and Gfeller (2007), in their review of National Academy of Neuropsychologists (NAN) professional members and fellows, found that the TOMM was the most frequently used test of effort. This finding was replicated in a UK study as reported by McCarter, Walton, Brooks, and Powell (2009). Full-Effort Group The full-effort group participants were given instructions to complete the tests to the best of their ability. Distraction Group Participants were instructed to complete all the tasks to the best of their ability and to complete the dual (distraction) task during the learning phases of both the TOMM and the WCT. The distraction group is

5 4 BARHON ET AL. therefore identical to the full-effort group apart the simultaneous completion of a distraction task. The distraction task was based on the paradigm suggested by Craik (1982). This task involved orally presenting a number between 1 and 9 every 3 s via a recording. Participants were requested to add 3 to each number and to say their response aloud. Accuracy was not recorded, as the task was simple and was used only as a distraction from the test being administered. The experimenter did, however, follow the responses of all participants to ensure that the majority of numbers were answered correctly and that few numbers were skipped. A practice trial was given before testing began, where the participant was presented just the distraction task for 15 s to ensure they understood the task. The instructions given to participants and the recording used in the present research were the same as that used by Batt et al. (2008), where randomly generated numbers were read at a flat tone onto a recorder. Batt et al. found that administration of a distraction task was a useful way of demonstrating that even when cognitive load was increased and attentional capacity was reduced, participants should be able to complete a measure of effort if it is primarily dependent on effort rather than ability. Although the use of a distraction task changes the nature of the test, the point of the distraction task in the current study was to test which measure was more resilient to interference and thus required less cognitive effort. Uncoached Group Participants in the uncoached group were instructed to simulate the cognitive effects of a TBI during the experiment to try and gain compensation for the injury while remaining undetected. This group was given the scenario taken from the study by Brennan et al. (2009), which asks the participant to simulate having significant brain damage during a cognitive assessment to gain a large settlement in a lawsuit. They are also warned that if they are detected by the examiner, they will lose the lawsuit so they are to simulate the damage in a believable way. Coached Group In addition to the instructions given to the uncoached group, participants in the coached group were prepared using the instructions taken from the study by DenBoer and Hall (2007). These instructions inform the participants of some of the typical symptoms of someone with a brain injury and remind them that major exaggerations such as remembering absolutely nothing will make the examiner easily identify that they are simulating. No further instructions about the level of performance typifying someone with a brain injury nor the methods or instruments used to identify malingering were provided. The authors reported a 20% reduction in ability to detect coached from uncoached malingerers when given those instructions. Participants were administered the demographic questionnaire, followed by the TOMM and WCT and lastly the manipulation check. The administrative order of the TOMM and WCT was counterbalanced between participants to reduce the potential for order effects. Data Analysis Data were analyzed using the Statistical Package for the Social Sciences (SPSS) Version 18. Initial analysis was performed using one-way analysis of variance (ANOVA), which was used to investigate the demographic characteristics of the group, overall group effects, and simple between-group contrasts. The dependent variables were scores on the WCT and on Trial 2 of the TOMM. The independent variable was group. The sensitivity and specificity of each test were examined using the MedCalc software ( RESULTS Participants included 25 males (27%) and 67 females (73%), with ages ranging from 17 to 51 years (M ¼ years, SD ¼ 4.12 years). Reported years of education ranged from 6 years to 20 years (M ¼ years, SD ¼ 1.64 years). Two participants who had less than 12 years of education were admitted to the university via an entry examination due to having a culturally diverse background with limited academic experience. There were 23 participants in the distraction group, 22 in the uncoached group, 24 in the coached group, and 23 in the full-effort group. The four groups did not significantly differ on age, F(3, 88) ¼ 0.83, p ¼.48, or education, F(3, 88) ¼ 0.43, p ¼.73. While the ratio of females to males was not equal (67:25) across the whole sample, of critical import was whether the sex ratio was independent of experimental group. A chi-square analysis revealed Pearson s v 2 (3, N ¼ 92) ¼ 2.135, p ¼.545, showing no evidence of sex ratio being anything other than independent of experimental group membership. There was no significant difference between males and females on the TOMM (F ¼ 2.74, p ¼.10) or the WCT (F ¼ 2.95, p ¼.09). The descriptive information pertaining to age, education, and sex within each group is presented in Table 1. Univariate ANOVA revealed a significant overall effect of group on test scores for Trial 1 of the TOMM, F(3, 88) ¼ 25.13, p <.0005, Trial 2 of the TOMM, F(3, 88) ¼ 33.48, p <.0005, and the WCT, F(3, 88) ¼ 24.21, p < There were also moderate effect sizes found for each of these effects with a partial eta-square of

6 COMPARISON OF THE TOMM AND THE WCT 5 Downloaded by [E. Arthur Shores] at 02:05 16 August 2014 TABLE 1 Descriptive Information on the Demographic Variables Within Each Group Distraction (n ¼ 23) TABLE 2 Means and Standard Deviations for Each Group on the TOMM and WCT Distraction Mean (SD) Uncoached (n ¼ 22) Uncoached Mean (SD) Coached (n ¼ 24) Coached Mean (SD) Full Effort (n ¼ 23) Age (years) Mean (SD) (1.93) (7.38) (3.15) (1.82) Range Education (years) Mean (SD) (1.93) (1.27) (1.96) (1.31) Range Sex Male n (%) 8 (35) 6 (27) 4 (17) 7 (31) Female n (%) 15 (65) 16 (73) 20 (83) 16 (69) SD ¼ standard deviation; n ¼ group sample size; % ¼ percentage. Full Effort Mean (SD) TOMM (3.88) (9.42) (10.49) (3.03) Trial 1 TOMM (2.56) (9.80) (11.79) (0.65) Trial 2 WCT (2.14) (9.46) (12.50) (0.71) TOMM ¼ Test of Memory Malingering; WCT ¼ Word Choice Test; SD ¼ standard deviation..46 on Trial 1 of the TOMM,.53 on Trial 2 of the TOMM, and.45 on the WCT. The means and standard deviations of each group on Trial 2 of the TOMM and the WCT are presented in Table 2. Between-group contrasts were performed using the multivariate analysis of variance procedure in SPSS to investigate all hypotheses. On Trial 2 of the TOMM, a statistically significant difference was found between the full-effort group and the uncoached group, F(1, 88) ¼ 44.59, p <.0005, and between the full-effort group and the coached group, F(1, 88) ¼ 62.91, p < Similarly, on the WCT, there was a statistically significant TABLE 3 Mean and SD of the Combined Groups on the TOMM Trial 2 and the WCT Mean TOMM Combined Full Effort (Full Effort þ Distraction) TOMM Simulators (Uncoached þ Coached) WCT Combined Full Effort (Full Effort þ Distraction) WCT Simulators (Uncoached þ Coached) TOMM ¼ Test of Memory Malingering; WCT ¼ Word Choice Test; SD ¼ standard deviation. SD TABLE 4 Number of Participants in Each Group Who Failed=Passed the TOMM and the WCT Passed TOMM and WCT Failed TOMM and WCT Passed TOMM and Failed WCT Failed TOMM and Passed WCT Full Effort Distraction Coached Uncoached Total 47 (51%) 37 (40%) 2 (2%) 6 (7%) TOMM ¼ Test of Memory Malingering; WCT ¼ Word Choice Test. difference found between the full-effort group and the uncoached group, F(1, 88) ¼ 39.55, p <.0005, and between the full-effort group and the coached group, F(1, 88) ¼ 41.04, p < As expected, there was no statistically significant difference between the full-effort and distraction groups on either the TOMM, F(1, 88) ¼ 0.34, p ¼.56, or the WCT, F(1, 88) ¼ 0.47, p ¼.50, or between the coached and uncoached groups on either the TOMM, F(1, 88) ¼ 1.20, p ¼.28, or the WCT, F(1, 88) ¼ 0.00, p ¼.98. Due to a lack of significant difference, the two groups applying full effort (full-effort and distraction groups) Score Control (cum. %) TABLE 5 Scores on the TOMM Trial 2 by Group Distraction (cum. %) Uncoached (cum. %) Coached (cum. %) Total (cum. %) 0 0 (0.0) 0 (0.0) 1 (4.5) 1 (4.1) 2 (2.2) 16 0 (0.0) 0 (0.0) 0 (4.5) 1 (8.3) 1 (3.3) 17 0 (0.0) 0 (0.0) 0 (4.5) 2 (16.7) 2 (5.4) 24 0 (0.0) 0 (0.0) 0 (4.5) 2 (25) 2 (7.6) 25 0 (0.0) 0 (0.0) 1 (9.1) 2 (33.3) 3 (10.9) 28 0 (0.0) 0 (0.0) 1 (13.6) 0 (33.3) 1 (12) 29 0 (0.0) 0 (0.0) 3 (27.3) 0 (33.3) 3 (15.2) 31 0 (0.0) 0 (0.0) 0 (27.3) 2 (41.7) 2 (17.4) 32 0 (0.0) 0 (0.0) 2 (36.4) 0 (41.7) 2 (19.6) 33 0 (0.0) 0 (0.0) 1 (40.1) 1 (45.8) 2 (21.7) 34 0 (0.0) 0 (0.0) 1 (45.5) 1 (50) 2 (23.9) 35 0 (0.0) 0 (0.0) 0 (45.5) 2 (58) 2 (26.1) 36 0 (0.0) 0 (0.0) 1 (50) 0 (58) 1 (27.2) 37 0 (0.0) 0 (0.0) 3 (63.6) 3 (70.8) 6 (33.7) 38 0 (0.0) 0 (0.0) 1 (68.2) 2 (79.2) 3 (37) 39 0 (0.0) 0 (0.0) 2 (77.3) 2 (87.5) 4 (41.3) 40 0 (0.0) 1 (4.3) 1 (81.8) 0 (87.5) 2 (43.5) 41 0 (0.0) 0 (4.3) 1 (86.4) 0 (87.5) 1 (44.6) 43 0 (0.0) 1 (8.7) 1 (90.1) 0 (87.5) 2 (46.7) 46 0 (0.0) 2 (17.4) 1 (95.5) 0 (87.5) 3 (50) 47 1 (4.3) 0 (17.4) 0 (95.5) 0 (87.5) 1 (51.1) 48 0 (4.3) 3 (30.4) 0 (95.5) 0 (87.5) 3 (54.3) 49 1 (8.7) 4 (47.8) 0 (95.5) 0 (87.5) 5 (59.8) (100) 12 (100) 1 (100) 3 (100) 37 (100) Total TOMM ¼ Test of Memory Malingering; cum. % ¼ cumulative percentage.

7 6 BARHON ET AL. TABLE 6 Scores on the WCT by Group Score Control Distraction Uncoached Coached Total 0 0 (0.0) 0 (0.0) 1 (4.5) 1 (4.2) 2 (2.2) 15 0 (0.0) 0 (0.0) 0 (4.5) 1 (8.3) 1 (3.3) 17 0 (0.0) 0 (0.0) 0 (4.5) 1 (12.5) 1 (4.4) 25 0 (0.0) 0 (0.0) 0 (4.5) 1 (16.7) 1 (5.4) 27 0 (0.0) 0 (0.0) 0 (4.5) 2 (25.0) 2 (7.6) 28 0 (0.0) 0 (0.0) 1 (9.1) 1 (29.2) 2 (9.8) 29 0 (0.0) 0 (0.0) 2 (18.2) 1 (33.3) 3 (13.0) 30 0 (0.0) 0 (0.0) 0 (18.2) 1 (37.5) 1 (14.1) 32 0 (0.0) 0 (0.0) 3 (31.8) 0 (37.5) 3 (17.4) 33 0 (0.0) 0 (0.0) 1 (36.4) 1 (41.7) 2 (19.6) 34 0 (0.0) 0 (0.0) 2 (45.5) 1 (45.8) 3 (22.8) 35 0 (0.0) 0 (0.0) 1 (50.0) 1 (50.0) 2 (25.0) 36 0 (0.0) 0 (0.0) 2 (59.1) 1 (54.2) 3 (28.3) 37 0 (0.0) 0 (0.0) 2 (68.2) 2 (62.5) 4 (32.6) 38 0 (0.0) 0 (0.0) 3 (81.8) 0 (62.5) 3 (35.9) 40 0 (0.0) 0 (0.0) 2 (90.1) 1 (66.7) 3 (39.1) 41 0 (0.0) 1 (4.3) 0 (90.1) 1 (70.8) 2 (41.3) 42 0 (0.0) 0 (4.3) 0 (90.1) 1 (75.0) 1 (42.4) 44 0 (0.0) 1 (8.7) 0 (90.1) 0 (75.0) 1 (43.5) 46 0 (0.0) 2 (17.4) 0 (90.1) 0 (75.0) 2 (45.7) 47 0 (0.0) 6 (43.5) 0 (90.1) 2 (83.3) 8 (54.3) 48 3 (13) 2 (52.2) 0 (90.1) 0 (83.3) 5 (59.8) 49 9 (52.2) 7 (92.6) 1 (95.5) 0 (83.3) 17 (78.3) (100.0) 4 (100.0) 1 (100.0) 4 (100.0) 20 (100.0) Total WCT ¼ Word Choice Test; cum. % ¼ cumulative percentage. were combined, and the two groups simulating a TBI (coached and uncoached) were combined for both the TOMM and the WCT (see Table 3). Subsequent analysis revealed there was a statistically significant difference between those applying full effort and those instructed to simulate on the WCT, F(1, 88) ¼ 72.11, p <.0005, as well as on the TOMM, F(1, 88) ¼ 98.14, p < Trial 2 of the TOMM has an established cut score of 45 out of 50 (Rees et al., 1998; Tombaugh, 1996), which was found to produce optimal specificity and sensitivity in the present sample. In participants applying full effort (n ¼ 46), there were no misclassifications from the full-effort group and two misclassifications from the distraction group. In those instructed to simulate cognitive impairment (n ¼ 46), 21 out of the 22 uncoached group members and 20 out of the 24 coached group members were correctly identified as applying suboptimal effort, revealing five false negatives in this sample. The results yielded a sensitivity of 89% (95% confidence interval [CI] [77%, 95%]) and specificity of 96% (95% CI [86%, 99%]). There is currently no defined cut score available for the WCT. Sensitivity and specificity were therefore used to identify an optimal cut point on the WCT to use as a diagnostic indicator of suspected simulation. A cut score of 42 (41 or less indicating a fail) was chosen as it produced the optimal point of sensitivity and specificity in the current sample. Of those who applied full effort (n ¼ 46), no participants from the full-effort group were misclassified as simulating and only 1 participant from the distraction group was misclassified as simulating. Therefore, applying the cut score of 42 resulted in only one false-positive classification. In the simulating conditions (n ¼ 46), 20 out of the 22 uncoached group members and 18 out of the 24 full-effort group participants were correctly classified as simulators, producing a total of eight false negatives. Using a cut score of 42 out of 50 resulted in a sensitivity of 83% (95% CI [69%, 91%]) and a specificity of 98% (95% CI [88%, 99%]). There was a 91% concordance between the two measures using the reported cutoff scores (45 on Trial 2 of the TOMM and 42 on the WCT). The WCT did not detect 7% of those who failed on the TOMM, and the TOMM did not detect 2% of those who failed on the WCT. The number and percentage of those who failed or passed either measure within each group is presented in Table 4. The cumulative percentages of scores within each group on each test are presented in Tables 5 and 6 to demonstrate the spread of performance within the TABLE 7 Sensitivity, Specificity, PPV, NPV, and Classification of Different Cut Scores on the TOMM Trial 2 Cut Score Sensitivity (95% CI) Specificity (95% CI) PPV (95% CI) NPV (95% CI) Classification (79.19, 97.53) (76.42, 96.33) (76.88, 96.41) (78.76, 97.47) (71.19, 97.53) (71.19, 97.53) (71.19, 97.53) (71.19, 97.53) (76.42, 96.33) (85.13, 99.34) (84.16, 99.30) (77.76, 96.56) (76.42, 96.33) (85.13, 99.34) (84.16, 99.30) (77.76, 96.56) (76.42, 96.33) (85.13, 99.34) (84.16, 99.30) (77.76, 96.56) (73.73, 95.03) (88.43, 99.64) (87.10, 99.59) (76.12, 95.53) (73.73, 95.03) (88.43, 99.64) (87.10, 99.59) (76.12, 95.53) (71.12, 93.63) (88.43, 99.64) (86.79, 99.58) (86.54, 94.39) (68.57, 92.16) (92.22, ) (90.66, ) (72.87, 93.36) (58.87, 85.72) (92.22, 100,00) (89.62, ) (66.64, 88.82) (51.98, 80.46) (92.22, ) (88.68, ) (88.68, ) PPV ¼ positive predictive value; NPV ¼ negative predictive value; TOMM ¼ Test of Memory Malingering; CI ¼ confidence interval.

8 COMPARISON OF THE TOMM AND THE WCT 7 TABLE 8 Sensitivity, Specificity, PPV, NPV, and Classification of Different Cut Scores on the WCT Cut Score Sensitivity (95% CI) Specificity (95% CI) PPV (95% CI) NPV (95% CI) Classification (73.73, 95.03) (65.00, 89.51) (66.28, 89.95) (72.64, 94.79) (68.57, 92.16) (79.19, 97.53) (77.36, 97.29) (70.88, 92.81) (68.57, 92.16) (85.13, 99.34) (83.05, 99.24) (71.91, 93.10) (68.57, 92.16) (85.13, 99.34) (83.05, 99.24) (71.91, 93.10) (68.57, 92.16) (88.43, 99.64) (86.47, 99.57) (72.40, 93.23) (68.57, 92.16) (88.43, 99.64) (86.47, 99.57) (72.40, 93.23) (68.57, 92.16) (88.43, 99.64) (86.47, 99.57) (72.40, 93.23) (63.63, 89.03) (92.22, ) (92.22, ) (69.60, 91.08) (56.54, 84.00) (92.22, ) (92.22, ) (65.27, 87.70) (56.54, 84.00) (92.22, ) (92.22, ) (65.27, 87.70) (49.75, 78.64) (92.22, ) (92.22, ) (61.50, 84.47) PPV ¼ positive predictive value; NPV ¼ negative predictive value; WCT ¼ Word Choice Test; CI ¼ confidence interval. Downloaded by [E. Arthur Shores] at 02:05 16 August 2014 current sample. Additionally, the sensitivity, specificity, PPV, and NPV of a range of cut scores on both the TOMM and the WCT are presented in Tables 7 and 8. The results of the current study, including the information on the predictive accuracy of the measures, was based on a nonclinical undergraduate sample and thus cannot be generalized to clinical or forensic samples. Results from the manipulation check revealed that there was at least moderate effort applied toward completing the experiment, F(3, 88) ¼ 1.04, p ¼.38, and that those in the groups asked to simulate a TBI found it more difficult to follow the instructions than did those who were instructed to apply full effort, F(3, 88) ¼ 11.97, p < DISCUSSION Detecting poor effort is often a difficult task and ensuring the implementation of valid and reliable tests is crucial. To ensure the ability of each test to distinguish simulators from those applying full effort, the effects of both distraction and coaching need to be investigated. The aims of the study were to examine the predictive validity of the WCT relative to the TOMM, by investigating the effect of a dual (distraction) task as well as coaching on the diagnostic accuracy of both tests in an attempt to compare the level of effort required to complete each of these measures. The final aim of the research was to establish an optimal cut score for the WCT, this being of potential importance to those using the test for clinical purposes. In keeping with the first hypothesis that the WCT would be as effective as the TOMM in detecting those simulating a TBI, the results indicated that 83% of those instructed to simulate impairment were accurately detected by the WCT compared with 89% detected by the TOMM. Although there were slightly more false negatives on the WCT, the difference between the two tests was not large enough to attain significance. The slightly lower sensitivity of the WCT in detecting those simulating a TBI in the current sample may have reflected factors other than those under investigation, such as sampling error, poor understanding of test instructions, or the fact that unlike the TOMM, the WCT is a single-trial task. Given that some studies using clinical and forensic TBI samples have found the TOMM to have a high rate of false positives, the WCT and other SVTs need to be further examined in these populations (Armistead-Jehle & Gervais, 2011; Gervais et al., 2004; Green, 2011). In line with the second hypothesis, a highly significant overall effect of group was revealed for both the WCT and the TOMM with almost identical scores obtained for the two groups applying full effort and almost identical scores for the two groups instructed to simulate a TBI. As expected, those groups applying full effort scored significantly higher compared with those instructed to simulate a TBI on both tests. Further, the WCT only misclassified one participant applying full effort as a simulator, whereas the TOMM misclassified two. Importantly, these three misclassified participants were from the distraction group, and there were no misclassifications from the full-effort group. The current results were consistent with those of a number of other studies investigating the efficacy of the TOMM (Iverson et al., 2010; Merten et al., 2007; Powell et al., 2004; Rees et al., 1998) and demonstrated that in undergraduate volunteer students, the TOMM is a reliable measure with which to compare performance on the WCT. In keeping with the third hypothesis that performance on the WCT and the TOMM would be unaffected by the dual (distraction) task, no significant difference was found between the distraction and full-effort groups on either measure. In relation to the TOMM, the current results replicated those reported by Batt et al. (2008). More importantly, however, the

9 8 BARHON ET AL. present results supported the contention that the WCT is a measure of effort and has little dependence on cognitive ability. The findings provide evidence for the construct validity of this measure. Although it is possible that the distraction task was not sufficiently difficult to impact participants ability to attend to the test, the dual (distraction) task used in the current research was identical to that used by Batt et al., who demonstrated that performance on the Word Memory Test (Green, Allen, & Astner, 1996) was significantly negatively affected by the task. The fourth hypothesis that both the TOMM and the WCT would be robust to the effects of coaching was strongly supported. There was no significant difference between those participants who were coached and those who were not coached on either the TOMM or the WCT. This indicates that with the coaching instructions given, participants who were coached were not able to better avoid being detected as applying poor effort compared with those who were not given any coaching on either measure. This finding has not been previously demonstrated for the WCT. Although similar findings have been reported for the TOMM (Jelicic et al., 2011; Powell et al., 2004; Weinborn, Woods, Nulsen, & Leighton, 2012), other studies have demonstrated that coaching can affect the test s predictive accuracy (Brennan et al., 2009; DenBoer & Hall, 2007; Sollman & Berry, 2011). The disparity in findings may be attributed to the different methods of coaching employed as well as whether a warning was given to participants regarding the potential for detection of poor effort (Weinborn et al., 2012). The availability of information regarding effort measures such as the TOMM is of significant concern as it facilitates lawyers to coach clients. Accordingly, there is an increasing need for newly developed and validated measures of effort, such as the WCT, to be implemented in clinical practice as this will minimize this risk for lawyers being able to readily identify and inform their clients about the measure. The final hypothesis that the TOMM and the WCT were equally able to detect the coached or uncoached participants simulating a TBI was partially confirmed, with the TOMM correctly classifying slightly more of those who were simulating a TBI compared with the WCT. The TOMM correctly identified 95% of the uncoached group and 83% of the coached group. The WCT, however, correctly classified 91% of the uncoached group and 75% of the coached group. Although the effect of coaching was not statistically significant in the present study, prior research has suggested that coaching may produce more sophisticated simulating of cognitive impairment associated with TBI (DenBoer & Hall, 2007; Jelicic et al., 2011; Powell et al., 2004). The TOMM correctly classified 95.7% of those applying full effort giving it quite a low rate of false positives. Fail rates were slightly different for the WCT and the TOMM, with the TOMM having been slightly more sensitive, although only by approximately 6%. It remains unclear whether this is due to the efficacy of the test or other factors such as the nature of the material comprising the measure. Word processing is automatic as demonstrated in cognitive tasks such as the Stroop task (MacLeod, 1991; Stroop, 1935). However, the superior recognition of pictures over words is also well demonstrated (Paivio, 1991; Shepard, 1967). There is currently no universally accepted cut score for the WCT; however, our findings are consistent with those of Miller et al. (2011), who also found a score of 41 or less to be indicative of an invalid performance. The consistency of our findings with those of Miller and colleagues provides further support for the generalizability of these findings regarding an acceptable cut score for the WCT. The current results indicated that a cut score of 42 out of 50 produced only one false positive. Kim et al. (2010) used a cut score of 42 out of 50 for the RMT, a measure very similar to the WCT. Batt et al. (2008) found the TOMM had a PPV of 73% at a base rate of 30%, whereas at the same base rate in the current sample, the PPV of the test was much higher at 90%. The current findings were slightly lower than those of O Bryant and Lucas (2006), who reported the TOMM to have a PPV of 98% at a base rate of 30%. The PPV obtained for the WCT was even higher than the TOMM, having been 94% at a base rate of 30%. Although the WCT has a high PPV within this sample, further research is needed to demonstrate its effectiveness as a measure of effort in clinical samples. Also, the WCT was only slightly less sensitive than the TOMM, with an NPV of 93%, compared with 95% for the TOMM using a base rate of 30%. Miller et al. (2011) reported a slightly lower sensitivity and specificity for the WCT. Thus, the validity indicators derived from the present sample need to be replicated in further research. The current research utilized an analogue design, with an attempt to simulate real-life situations under controlled conditions (Cochrane, Baker, & Meudell, 1998; Larrabee, 2007) to investigate the predictive accuracy of the WCT as well as its robustness to coaching and distraction. To date, this is the first time that these properties of the WCT have been investigated. The WCT has the advantage of being relatively new and not widely known in the medico-legal setting. Currently, little information about the test is available via the Internet, unlike the detailed information relating to the TOMM, which is readily available on the Internet and in books and is well known by attorneys (Bauer & McCaffrey, 2006; Brennan et al., 2009; Russler et al.,

10 COMPARISON OF THE TOMM AND THE WCT ). Further, Miller and colleagues (2011) demonstrated that the WCT added incremental value to the predictive accuracy of the Wechsler Memory Scale-Fourth Edition. The results of the current study were consistent with all hypotheses and provided preliminary data to support the clinical utility of the WCT. Although the study made an important contribution to establishing the WCT as a reliable measure of simulation, there are a number of potential limitations that need to be addressed. The use of analogue research on simulation may limit the generalizability of the results; however, attempts to control these potential limitations as suggested in the criteria by Rogers (1997) were implemented in the experimental design. Although a simulation design can have very high internal validity, it often is restricted by low external validity. The use of simulators as opposed to true malingerers can often overestimate the discriminatory abilities of the tests, meaning it can inflate the obtained specificity (Bender, 2008; Larrabee, 2007). The use of simulators may also mean participants do not have enough motivation to truly replicate the behavior of a malingerer who may be rewarded with significant financial benefits for effectively malingering and who have the threat of severe consequences if detected (Larrabee, 2007; Powell et al., 2004). It is recognized that the coaching instructions given were simple and brief, and this may have not been enough to produce effective feigning of impairment on these measures. Although external validity may be low, experimenters can be relatively sure that the changes observed in the dependent variables (scores on the WCT and the TOMM) are a result of the experimental manipulations, which is a key advantage of using a simulation design. Thus, in the current research, between-group differences are most likely to be solely explained by the different instructions provided to the groups. Further, as the research utilized a simulation design in which participants were all from a nonclinical setting and were allocated to a specific group, the researcher can be confident in the group membership of each participant. Although it is not known whether those in the control group were truly applying effort, inspection of the results revealed that all members of the control group had a near-perfect score. As identified by Weinborn et al. (2012), it is also possible that the resistance to coaching may have been due to the type of coaching provided to the participants. Future research should therefore investigate the effects of more thorough coaching scenarios as well as investigate any differences on these measures between symptom- and test-based coaching. Future research should consider including a simulation group given a distraction manipulation task to address the effect of distraction on unmotivated individuals. Typically, effort measures are administered in the context of a full neuropsychological test battery. Administration of such tests in isolation or in a relatively small battery provides a less realistic picture of how they contribute to the results of an assessment and does not provide insight into whether the inclusion of such measures affects performance on other tasks. Using a full battery was not practical for the purpose of this assessment, especially given the fact that a nonclinical sample was utilized, and future research should look to further investigate the effects of coaching and distraction on the WCT in the context of a full battery. The use of a student sample in the present study was effective in establishing the predictive accuracy of a newly published measure in a design where the group membership was known. Future research should look to include a clinical sample to compare to the performance of the simulating malingerers. The results of the current research contribute to the expanding literature validating current methods of detecting poor effort. The WCT was found to be as effective as the TOMM in differentiating simulators from participants applying full effort, supporting the results reported by Miller et al. (2011). Moreover, the results of the current study supported the contention that, as with the TOMM, the WCT is primarily a measure of effort rather than cognitive ability. This is important given the frequency with which the WCT will potentially be used in assessing individuals with cognitive impairment secondary to brain injury. REFERENCES An, K., Zakzanis, K. K., & Joordens, S. (2012). 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